1. Field of the Invention
The present invention generally relates to a cassette for accommodating a length of inked ribbon for use with a thermal wax transfer printer and also to a printer mechanism operable with the ink ribbon cassette.
2. Description of the Prior Art
Printers capable of printing video signals on recording media in full color are now widespread. Although the present invention is applicable in general to a thermal wax transfer printer, in discussing the prior art pertinent to the present invention reference will be made to a so-called "video printer" capable of making a full-color print of a picture captured from a television receiver set or a video camera.
The conventional video printer generally comprises a sheet supply unit adapted to accommodate a stack of recording sheets; a thermal print head supported for movement between print and retracted positions at a printing station; a platen disposed at the printing station and cooperable with the thermal print head, when the latter is moved to the print position, to allow an ink material to be transferred from the length of inked ribbon onto one of the recording sheets then fed to the printing station; a first guide mechanism extending between the sheet supply unit and the printing station; a second guide mechanism extending from the printing station to a temporary storage position defined on one side of the printing station remote from the first guide mechanism; and a reversible feed means for feeding the recording sheets one at a time towards the temporary storage position along the first guide mechanism and then along the second guide mechanism and also for feeding the recording sheet backwards from the temporary storage position towards a sheet recovery position past the printing position once the recording sheet has been fed to the temporary storage position.
The prior art ribbon cassette accommodating therein a reeled length of inked ribbon for use in the video printer will be discussed with reference to FIGS. 14 and 15. As shown therein, the ribbon cassette generally identified by 8 comprises substantially cylindrical take-up and supply casings 2 and 4 spaced a part from each other so as to extend parallel to each other. The cylindrical take-up and supply casings 2 and 4 are connected together by means of a generally elongated front end plate having its opposite end portions thereof closing respective front open ends of the cylindrical casings 2 and 4, and a slender bridge 6 having its opposite ends rigidly connected with, or otherwise integrally formed with respective rear ends of the cylindrical casings 2 and 4. The take-up and supply casings 2 and 4 have take-up and supply spools 32 and 34 each rotatably accommodated within the corresponding casing and also have respective slots 2a and 4a defined therein so as to extend parallel to the longitudinal axis of the corresponding casings 2 and 4.
As clearly shown therein, the take-up and supply slots 2a and 4a in the take-up and supply casings 2 and 4, respectively, are located at the same level beneath the plane containing the respective longitudinal axes of the take-up and supply casings 2 and 4 (or those of the take-up and supply spools 32 and 34), and opens laterally outwardly so as to confront with each other. The slender bridge 6 have its opposite ends positioned adjacent the take-up and supply slots 2a and 4a and extend parallel to and beneath that plane containing the respective longitudinal axes of the take-up and supply casings 2 and 4. Hence, that portion of the reeled length of inked ribbon 26 between the supply and take-up slots 4a and 2a extends parallel to and below that plane.
As shown in FIG. 15, let it be assumed that the thermal print head 40, the platen 42 and the pinch and capstan rollers 46 and 44 occupy respective predetermined positions inside the video printer as shown therein. When the prior art ribbon cassette 8 of the above described construction is inserted into the video printer, the thermal print head 40 in the retracted position assumes a position above the slender bridge 6 and both of the pinch and capstan roller pair 46 and 44) and the platen 40 assumes respective positions below the slender bridge 6. Even though the prior art video printer in combination with the prior art ribbon cassette works satisfactorily, the prior art video printer is of a size having a relatively great height or thickness above a support surface on which it is placed since both of the pinch and capstan roller pair and the platen 42 must necessarily be disposed below the bottom plane of the slender bridge 6. If they are not so disposed, the ribbon cassette being inserted into the video printer will collide against the platen 42 and at least the pinch roller 46 and will be unable to reach a completely inserted position.
Thus, the prior art video printer requires a relatively large space for accommodating the thermal print head 40 in the retracted position and, also, at least the pinch roller 46 and the platen 42, in order for the prior art ribbon cassette 8 to be smoothly inserted into the video printer to reach the completely inserted position. This brings about an increase in thickness or height of the video printer as a whole.